Immuneering Presents Design and Methodology of Ongoing Phase 3 MAPKeeper 301 Trial at ESMO Congress 2026

– Ongoing Pivotal Phase 3 trial evaluating atebimetinib in combination with modified gemcitabine/nab-paclitaxel versus standard-of-care chemotherapy in first-line metastatic pancreatic cancer –

-MAPKeeper 301 builds on encouraging Phase 2a results presented at ASCO 2026 including median overall survival (OS) of 17.3 months –

– Global, randomized Phase 3 trial ongoing, with overall survival as the primary endpoint –

NEW YORK, Oct. 26, 2026 (GLOBE NEWSWIRE) — Immuneering Corporation (Nasdaq: IMRX), a late-stage clinical oncology company focused on keeping cancer patients alive and helping them thrive, today announced that a trial-in-progress poster describing the design and methodology for MAPKeeper 301, its ongoing pivotal Phase 3 clinical trial evaluating atebimetinib in combination with modified gemcitabine and nab-paclitaxel (mGnP) in first-line metastatic pancreatic ductal adenocarcinoma (PDAC), was presented at the European Society for Medical Oncology (ESMO) Congress 2026 held October 23-27, 2026 in Madrid, Spain.

MAPKeeper 301 is a global, randomized, open-label, multicenter Phase 3 trial designed to evaluate whether atebimetinib, an investigational, once-daily oral deep cyclic inhibitor of MEK, in combination with mGnP can improve overall survival compared with standard-of-care gemcitabine and nab-paclitaxel (GnP) in patients with previously untreated metastatic PDAC.

The trial builds on encouraging results from Immuneering’s ongoing Phase 2a study of atebimetinib in combination with mGnP, which were reported at ASCO in June and demonstrated median overall survival of 17.3 months, median progression-free survival of 8.3 months, an objective response rate of 36% and a disease control rate of 82% among 55 patients. These results compare favorably with historical outcomes for standard GnP, although the studies were not conducted head-to-head.

“Pancreatic cancer remains one of the most difficult cancers to treat, and patients with metastatic disease in the first-line setting urgently need new therapies capable of delivering meaningful improvements in survival,” said Ben Zeskind, Ph.D., Co-founder and Chief Executive Officer of Immuneering. “Our encouraging Phase 2a results reported at ASCO, including median overall survival of 17.3 months in first-line pancreatic cancer patients, provide a strong foundation for MAPKeeper 301. This pivotal Phase 3 trial is designed to determine whether atebimetinib, in combination with modified chemotherapy, can extend survival compared with the current standard of care. We believe atebimetinib’s differentiated Deep Cyclic Inhibition mechanism, designed to shrink tumors durably, preserve body mass, and minimize side effects, has the potential to transform the treatment of metastatic pancreatic cancer.”

ESMO Congress 2026 Poster Presentation Details:

Title: MAPKeeper 301: A Phase 3 Randomized, Open-Label Study of Atebimetinib in Combination with the Modified Gemcitabine and nab-Paclitaxel Regimen Versus Standard Gemcitabine and nab-Paclitaxel for Treatment of Patients with Metastatic Pancreatic Ductal Adenocarcinoma
Abstract Number: 3189TiP
Presentation Type: Trial in Progress
Presentation Date: October 25, 2026
The poster will be available on the publications section of Immuneering’s website following presentation at https://immuneering.com/publications

About MAPKeeper 301

MAPKeeper 301 is a global, randomized, open-label, multicenter Phase 3 clinical trial evaluating atebimetinib in combination with modified gemcitabine and nab-paclitaxel compared with standard gemcitabine and nab-paclitaxel in patients with previously untreated metastatic pancreatic ductal adenocarcinoma.

Patients are randomized 1:1 to receive either:

• Experimental arm: Atebimetinib 320 mg orally once daily in combination with modified gemcitabine 1,000 mg/m² and nab-paclitaxel 125 mg/m², administered on days 1 and 15 of each 28-day cycle.
• Control arm: Standard-of-care gemcitabine 1,000 mg/m² and nab-paclitaxel 125 mg/m², administered weekly for three consecutive weeks followed by one week off.

Randomization is stratified by geography, presence of liver metastases, Eastern Cooperative Oncology Group (ECOG) performance status, and whether metastatic disease is newly diagnosed or recurrent.

The primary endpoint is overall survival. Secondary endpoints include progression-free survival, overall response rate, disease control rate, safety, and quality of life.

Eligible patients must have confirmed metastatic pancreatic adenocarcinoma, measurable disease and an ECOG performance status of 0 or 1 and must not have received prior systemic anticancer therapy.

The study began dosing patients in June 2026 and is currently recruiting patients. Additional information is available at www.mapkeeper301.com and ClinicalTrials.gov (NCT07562152).

About Immuneering Corporation

Immuneering is a late-stage clinical oncology company dedicated to keeping cancer patients alive and helping them thrive, with an initial focus on patients with RAS, RAF, and other MAPK-driven cancers. The Company is developing an entirely new category of cancer medicines, Deep Cyclic Inhibitors, designed to improve overall survival by three mechanisms: shrinking tumors durably with less resistance, preserving body mass by countering cachexia, and minimizing side effects to maximize performance status and combinability. Immuneering’s lead product candidate, atebimetinib, is an oral, once-daily Deep Cyclic Inhibitor of MEK, designed to improve survival across many cancer indications. The Company is conducting a global randomized pivotal trial, MAPKeeper 301, evaluating atebimetinib in combination with chemotherapy in first-line pancreatic cancer patients. The Company’s development pipeline also includes additional combination opportunities and preclinical stage programs. For more information, please visit www.immuneering.com.

Forward-Looking Statements

This press release contains forward-looking statements, including within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including, without limitation, statements regarding: the treatment potential of atebimetinib, alone or in combination with other agents to treat cancer including modified Gemcitabine/nab-paclitaxel (mGnP); the Phase 2a results presented at ASCO providing a strong foundation for the MAPKeeper 301 trial; the unmet need and that patients with metastatic disease urgently need new therapies capable of delivering meaningful improvements in survival; the trial design, enrollment progress, and timing of results from the MAPKeeper 301 trial.

These forward-looking statements are based on management’s current expectations. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including, but not limited to, the following: we are a late-stage clinical oncology company with a limited operating history and have not completed any registrational clinical trials; we have incurred significant losses, are not currently profitable and may never become profitable; limitations on our cash runway and potential increases in expenditures; our need for additional funding; our unproven approach to therapeutic intervention; our ability to address regulatory questions and changing regulatory standards, and the uncertainties relating to regulatory filings, reviews and approvals; the lengthy, expensive, and uncertain process of clinical drug development, including the uncertainty of whether positive preclinical or early clinical efficacy and safety results are confirmed in later-stage trials, potential delays in activation of trial sites or enrollment of trial participants, or failure to obtain regulatory approvals; our reliance on third parties and collaborators to conduct our clinical trials, manufacture our product candidates, and develop and commercialize our product candidates, if approved; failure to compete successfully against other drug companies; protection of our proprietary technology and the confidentiality of our trade secrets; potential lawsuits for, or claims of, infringement of third-party intellectual property or challenges to the ownership of our intellectual property; our patents being found invalid or unenforceable; costs and resources of operating as a public company; and unfavorable or no analyst research or reports.

These and other important factors discussed under the caption “Risk Factors” in our Quarterly Report on Form 10-Q for the period ended June 30, 2026, and our other reports filed with the U.S. Securities and Exchange Commission, could cause actual results to differ materially from those indicated by the forward-looking statements made in this press release. Any such forward-looking statements represent management’s estimates as of the date of this press release. While we may elect to update such forward-looking statements at some point in the future, except as required by law, we disclaim any obligation to do so, even if subsequent events cause our views to change. These forward-looking statements should not be relied upon as representing our views as of any date subsequent to the date of this press release.

Investor Contact:
Laurence Watts
New Street Investor Relations
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Media Contact:
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